Seals have been utilized for years in hydraulic and pneumatic devices to prevent the pressurized fluid in the devices from migrating between sections within the device and between the device and the environment. These seals include the shaft seals for rotating shafts protruding from the device so as to allow a rotary input/output without leakage. These shaft seals are typically a circular ring of the resilient material (normally rubber or a synthetic polymer) surrounding the rotating shaft set into a seal carrier or pocket in the fixed housing. However the resilient material frequently can not stand against the pressure exerted upon it; the side load against a shaft seal frequently is many thousands of pounds at the 1000-2000 PSI typically used within the devices. Therefore a backup ring of some nature is normally included with the shaft seal to reinforce the shaft seal. The backup rings themselves, however, are critical components subject to wear, binding, abrasion, and other problems. Rulons are also used to strengthen the seal. One common Rulon is an "L" shaped Teflon Rulon cast into the material of the seal (after first etching the back side of the Rulon for adherence). This Rulon, however, is difficult to manufacture and is also subject to flex differentiation breakdown, wear and other problems.
In addition, the seal itself can be located in a seal carrier necessitating an additional part for manufacture and assembly such as in U.S. Pat. No. 4,285,643, Rotary Fluid Pressure Device. The seal and/or shaft can also be inaccessible without major disassembly of the device such as in U.S. Pat. No. 4,533,302, Gerotor Motor. This precludes easy replacement of the shaft, seal, bearings, wobblestick, and other drive components without complete disassembly of the device.